Research: Science & Education
The Importance of Undergraduate General and Organic Chemistry to the Study of Biochemistry in Medical School Anthony Scimone and Angelina A. Scimone Department of Chemistry, Caldwell College, Caldwell, NJ 07006 Much literature has been devoted to the problems associated with teaching undergraduate chemistry courses. General chemistry reform has been called for by the Committee on Professional Training (1), the American Chemical Society (2), the American Association for the Advancement of Science (3), the National Science Foundation (4), Sigma Xi (5), the Worchester Polytechnic Institute (6), and individual authors (7–13). Organic chemistry reform is not as well documented, but does include proponents from some of the above authors (8, 14) and professional societies (2–5). In the early 1990s, the ACS established a task force to investigate the need for change in the general chemistry curriculum. No such task force currently exists to evaluate undergraduate organic chemistry course. A 1991 general chemistry curriculum survey was distributed to chemists and engineers (9). The present survey built on earlier efforts to reform undergraduate chemical curricula by both inquiring about a greater number of more specific topics and extending the list of topics to organic chemistry. Methods and Sources of Data To investigate those chemistry topics necessary to facilitate the study of biochemistry in U.S. medical schools, selected faculty members in the biochemistry departments of 122 U.S. medical schools were surveyed for their opinions. Biochemistry was chosen because it, among all courses taught in medical school, relies the most on general chemistry nd organic chemistry concepts. Two surveys (one considering general chemistry topics and the other, organic chemistry topics) were sent to each department chair with the instruction that it should be completed by a faculty member who is currently teaching biochemistry to medical students. The survey statement read: “Understanding of the following general (or organic) chemistry topics is necessary for understanding the components of the biochemistry course at your medical school.” The responses were graded 1 (strongly agree, i.e., the topic is essential to understanding the biochemistry course in your medical school), 2 (agree, i.e., important), 3 (disagree, i.e., supplemental), and 4 (strongly disagree, i.e., irrelevant). An arithmetic mean score was computed for each question. From all of these averaged scores a mean (the “mean of means”) and standard deviation were obtained using the STATDISK program. A topic was categorized as “especially important” if its averaged score fell below one standard deviation of the mean of the means. Conversely, a topic was categorized as “especially unimportant” if it received a score above one standard deviation of the mean of means. These cutoffs were chosen to allow for comparison between our survey and previous data (9).
Results Of the 122 pairs of surveys sent to medical school biochemistry departments, 71 general chemistry and 72 organic chemistry surveys were returned. These response rates (both 58%) are a bit higher than the 26% for the previously published C&E survey (9). Very few items were left blank in the present surveys. (Faculty members were instructed to leave an item blank if they were unfamiliar with or had no opinion about a topic.) The results of the general chemistry surveys yielded a mean of means of 2.12 and a standard deviation of 0.63. A graph of the average scores is bell-shaped yet positively skewed (Fig. 1). The cutoffs were therefore 1.49 to 2.75, and averaged scores below 1.49 were indicative of a general chemistry topic that was especially important for the study of biochemistry in medical school. Conversely, scores above 2.75 meant the topic was especially unimportant. Results for the organic chemistry survey were similarly calculated, and topics scoring below 1.95 were labeled especially important while those scoring above 3.33 were especially unimportant. A graph of these data is also bell-shaped; however it is not as positively skewed (Fig. 2). The especially important and unimportant topics are listed in Tables 1 through 4. Discussion We hope that the present investigation will serve to emphasize those topics that are genuinely essential to understand for eventual medical study. It is interesting that, on the whole, general chemistry topics were considered slightly more important than organic chemistry topics (Figs. 1 and 2). One potential source of error in our surveys lies in the relatively low percentage of responders to the survey (58%) despite follow-up requests. Another potential source of error stems our sending only one set of surveys to each medical school, thereby limiting ourselves to the opinion of one faculty member per medical school, rather than a consensus of the entire biochemistry faculty. (This is an especially important consideration because many medical school biochemistry courses are team taught.) However, a survey of six members within a single biochemistry department showed no significant difference between the overall department average and the national average (Table 5). Our data reflected that (i) most survey topics fall within one standard deviation of the mean (63% for general chemistry, 57% for organic chemistry; normal Gaussian distribution holds 68% of data within this range); and (ii) significant percentages of topics are considered especially unimportant by our criteria (19% and 22% from general chemistry and organic chemistry, respec-
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Table 1. Especially Important Topics in General Chemistry Metric units Molecular weight Mole concept and Avogadro’s number Ionic bond Covalent bond Hydrogen bonding Van der Waal’s forces Molarity Ionization of water Definition and calculation of pH, pOH Zwitterrions Weak acids: pH calculations and dissociation Figure 1. General chemistry topic scores.
pH calculations of salts of weak acids and bases Buffers (definition, simple calculations) Celsius temperature scale Free energy Standard ∆G and spontaneity of reaction Rate dependence on concentration Rate law, rate constant, order of reaction First order kinetics Rate determining step Catalysts Relationship of Keq and standard ∆G
Figure 2. Organic chemistry topic scores.
tively). Many of the especially unimportant general chemistry topics were physical chemistry concepts (e.g., calorimetry, phase diagrams, physical properties of elements, and compounds) as well as periodicity. This may reflect the more general view that general chemistry has been overly devoted to physical chemistry at the expense of inorganic and organic concepts (7, 9, 10, 12, 13). The organic chemistry topics considered unimportant were almost entirely related to synthesis; a very few were mechanism topics. Whereas organic synthesis per se seems to have straightforward industrial application, the in vivo counterparts to those syntheses are uncannily similar, and these similarities could possibly be commented upon, even if only briefly, during the organic chemistry course. These parallels facilitate learning the biochemistry syntheses in medical school—or in any graduate biochemistry course. It is true that undergraduate chemistry departments must instruct more types of students than just premedical students, and that premedical students must be more broadly prepared to enter the work force in the event they are not admitted into medical schools; but given that premedical student enrollment is rising and that these students comprise a substantial percentage (if not an outright majority) of students in general and
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organic chemistry classes, then serving this population by carefully teaching these prerequisite chemistry courses is warranted. Careful teaching requires that the undergraduate chemistry instructor respond to the changes that periodically occur in medical curricula by teaching undergraduate chemistry topics that have medical relevance. Students intending to study graduate chemistry or engineering can take advantage of advanced courses that cover topics more suited to their specialities, but premedical students are required to take only general and organic chemistry to satisfy medical school admission requirements, and so are likely to be exposed to chemistry only during these two courses. Based on the survey data, we suggest that in teaching undergraduate general or organic chemistry, the topics categorized as exceptionally important should definitely be included in the curriculum. Those considered to be exceptionally unimportant need further evaluation; they could possibly be moved to advanced undergraduate courses. Of course, an alternative approach is to require that premedical students take undergraduate biochemistry; however medical school admission requirements are already heavy in chemistry courses to the exclusion of biology and physics. Conclusion While this investigation regarded only the opinions of medical biochemistry faculties in rating specific undergraduate general and organic chemistry topics according to relative importance, it would be of benefit to similarly survey other types of post-undergraduate fac-
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Research: Science & Education
Table 2. Especially Important Topics in Organic Chemistry Absolute configuration @ alpha carbon (amino acids) Amino acids as zwitterions
Table 3. Especially Unimportant Topics in General Chemistry Transition metals/compounds physical properties
Amino acid sidechain typing (acidic, hydrophobic, etc.)
Halogens/compounds physical properties
Oxidation of cysteine to cystine
Alkali metals/compounds physical properties
Peptide link (formation, hydrolysis)
Lab use of balance
Amide stability, rotation around amide bond
Lab use of manometer
Primary, secondary, tertiary protein structures
Lab use of paper chromatography
H–, S–S, hydrophobic bonds in tertiary structure
Solubility of anions/precipitates
Isoelectric point
Commerical chemical processes (e.g., steel)
Carbohydrate nomenclature/common names
Filtration methods
Absolute configuration in carbohydrates
Ionization energy trends in the periodic table
Cyclic nature and conformations of hexoses
Network bond (e.g., sand)
Epimers and anomers
Geometry prediction from electron pair repulsion
Glycosidic linkage hydrolysis
Ionic radius trends in the periodic table
Structure of steroid nucleus
Physical property trends in the periodic table
Structure of triacylglycerols
Paramagnetism and diamagnetism
Common fatty acids
Phase diagram, heats of fusion and vaporization
Cis/trans fatty acids
Raoult’s Law of vapor pressure lowering
Phosphoric anhydrides and esters hydrolysis
Ionic lattices
Acetals/ketals
Oxidation states of halogen acids
Hemiacetals/hemiketals
Metallurgy
Imines/Schiff bases
Plasma (ionized matter) chemistry
Keto-enol tautomerism
Calorimetry (heat capacity, specific heats)
Beta keto acid decarboxylation
Coefficient of expansion of metals
Structural isomerism in organic compounds Stereoisomerism, chirality Diastereomers Enantiomers Drawing Fisher projections Electrophoresis
ulties (e.g., dental and veterinary schools, and graduate schools in chemical, chemical engineering, and biological fields). This would lead to a more thorough systematic approach to undergraduate chemistry reform. Acknowledgments We would like to thank the faculties of the responding biochemistry departments for their time in completing a lengthy questionnaire. We also thank Caldwell College for supplying financial support for the mailings and J. Armstrong and L. Dickinson for computer assistance. We thank E. Alger, University of Medicine and Dentistry of New Jersey, Newark, for helpful discussions.
Literature Cited 1. A CPT Commentary on Introductory Chemistry: Is There A Problem? Committee on Professional Training Newsletter 1990, 6, 1–2. 2. (a) Educational Policies for National Survival; A Statement of the ACS; American Chemical Society: Washington, DC, 1989; (b) Examining the Organic Chemistry Lecture Course; ACS Symp.; American Chemical Society: Washington, DC, 1994; c. Illman, D. Chem. Eng. News 1994, 73(36), 39–40. 3. The Liberal Art of Science–Agenda for Action; American Association for the Advancement of Science: Washington, DC, 1990. 4. Report on NSF Undergraduate Curriculum Development Workshop on Materials; National Science Foundation: Washington, DC, 1990. 5. An Exploration of the Nature and Quality of Undergraduate Education in Science, Mathematics and Engineering; Sigma XI: New Haven, CT, 1989. 6. Beall, H. J. Chem. Educ. 1991, 68, 835–837. 7. Gillespie, R. J.; Humphreys, D. A. J. Chem. Educ. 1993, 70, 528–530. 8. Hawkes, S. J. J. Chem. Educ. 1992, 69, 178–181. 9. Kreyenbuhl, J. A.; Atwood, C. A. J. Chem. Educ. 1991, 68, 914–918. 10. Spencer, J. N. J. Chem. Educ. 1992, 69, 182–186. 11. Bodner, G. M. J. Chem. Educ. 1992, 69, 186–190. 12. Gillespie, R. J. J. Chem. Educ. 1991, 68, 192–194. 13. Lloyd, B. W. J. Chem. Educ. 1992, 69, 633–638. 14. Sartoris, N. E. J. Chem. Educ. 1992, 69, 750–752.
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Table 4. Especially Unimportant Topics in Organic Chemistry Lucas test for tertiary alcohols Alcohol synthesis from borohydrides and carbonyls Alcohol synthesis from Grignards and esters Alcohol synthesis from halocarbon hydrolysis Aldehyde synthesis from oxidation of alcohols Wittig reaction (phosphonium ylides) Iodoform reaction (methyl ketone to acid) Semicarbazone formation Clemmensen, Wolff–Kirschner carbonyl reduction Grignard basicity, reactions Carboxylic acids from KMnO4 and toluene Alcohols from nitriles and Grignard reagent Carbonyls from nitrile reduction (via imine) Nitrile hydrolysis to carboxylic acid Ethers from alcoholates and halocarbons
Table 5. Comparison of Survey Results Between a Single Faculty and All Faculty Responders Six Membered Faculty
Ethers from dehydration of alcohols
National
Q valuea
Amines from tin reduction of nitrobenzenes
General chemistry
1.66 ± 0.44
2.12 ± 0.63
2.37
Diazonium ion reactions
Organic chemistry
2.08 ± 0.70
2.64 ± 0.69
1.88
Alkyne hydration
a
Difference between the means at alpha = 0.018.
Terminal acetylenes: acidity, nucleophilicity Diels–Alder, pericyclic reactions Hofmann–Zaytseff rules of elimination Elcb elimination mechanism Dissolving metal reduction: dearomatization Benzyne, nucleophilic aromatic substitution Carbene chemistry Structural determinations from ozonolysis Alkyne hydrogenation (cis/trans catalysts) Organocopper reagents Organocadium reagents Organozinc reagents Multistep syntheses Commercial organic processes (e.g., petroleum)
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